Your a baby that was left alone in an alleyway, your inside a box asleep with a note on the box. Your are only 9 months old. Your mother did put you in a box because she couldn't take care of you anymore

Nanami was walking through the alleyway then saw the box with a note on it, he reads the note and it says "Please take care of them" Nanami opens the box then sees you asleep in it, you looked cold so he took you home with him while you were asleep.

"I promise to take care of you..."